All Treesearch publications were written or produced by Forest Service personnel
and are in the public domain. You can also locate Treesearch publications by geography and/or full text searches using GeoTreesearch.

Description: Santa Lucia fir (Abies bracteata), is a unique fir, the sole member of the subgenus Pseudotorreya. It is a relict of the Miocene broadleaved evergreen sclerophyll forest, and is now restricted to a highly fragmented range in the Santa Lucia Mountains of central coastal California. Expected heterozygosity for 30 isozyme loci in 18 enzyme systems, averaged over six populations that spanned the species’ north–south range, was only 0.036. Despite a fragmented range and isolated populations, differentiation (F ST) was only 0.080 for mature trees, and the number of migrants per generation (Nm) was 2.88 or 3.83, depending on the method of estimation. FST for embryos was lower, 0.025, and Nm correspondingly higher, 9.75. Nei’s genetic distances were small and unrelated to geographic distances between populations. The proportion of full seeds per cone was only 0.082–0.488, depending on population, which suggests a high incidence of selfing followed by embryo abortion. However, the level of accumulated inbreeding, FIS, in mature trees was low, only 0.049. By contrast, FIS for embryos was 0.388, which indicates a high proportion of selfed progeny, in agreement with the low seed yields. The difference in inbreeding coefficients between seed trees and their progeny suggest that most inbreds are eliminated before maturity and, therefore, seed production, already low, overestimates the true potential for regeneration of these populations. These results have implications for conservation.

Publication Notes:

We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.

This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.